Greg Smith wrote: > Tom Lane wrote: > > You've got entirely too simplistic a view of what the "delta" might be, > > I fear. In particular there are various sorts of changes that involve > > inserting the data carried in the WAL record and shifting pre-existing > > data around to make room, or removing an item and moving remaining data > > around. If you try to replay that type of action against a torn page, > > you'll get corrupted results. > > > > I wasn't sure exactly how those were encoded, thanks for the > clarification. Given that, it seems to me there are only two situations > where full_page_writes is safe to turn off: > > 1) The operating system block size is exactly the same database block > size, and all writes are guaranteed to be atomic to that block size. Is that true? I have no idea. I thought everything was done at the 512-byte block level. -- Bruce Momjian <bruce@xxxxxxxxxx> http://momjian.us EnterpriseDB http://enterprisedb.com + It's impossible for everything to be true. + -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
